The City’s bill for damages stemming from a water main break that flooded dozens of West Portal homes in February is at $5.5 million and counting. But officials promise it will be paid by the engineering firm they believe is responsible for the break.

First installed in 1952, the 16-inch cast-iron pipe underneath 15th Avenue at Wawona Street “pulled apart at a joint” Feb. 27. The subsequent flood of water left a huge hole in the street and damaged 23 homes, some of which had to be red-tagged after the water caused their foundations to shift.

The block had been dug up by work crews multiple times in the months prior, The San Francisco Examiner reported in April. In June, the San Francisco Public Utilities Commission informed Precision Engineering, the firm contracted to work on a sewer main that runs close to the water main, that workers “failed” to ensure the pipe’s safety when it was exposed during construction.

Precision was awarded the contract in early 2012 and dug up the street between October and November of that year, according to records.

The bill so far includes $3 million just to repair the main and replace the street, sidewalks and other city-owned assets, according to the SFPUC.

The bill will be much higher once “multimillion-dollar” settlements from residents whose homes have been rendered uninhabitable are included, according to The City.

A total of 74 damage claims have been filed against San Francisco by property owners, the City Attorney’s Office said. More could be filed in the coming months.

In addition to small payouts of $25,000 to residents for damage to clothing, cars and other possessions, The City has already paid out $300,000 to one homeowner whose foundation was damaged, according to SFPUC spokesman Tyrone Jue. Another claim, for $40,000, is close to being finalized.

Lawyers for Precision and The City are currently negotiating a settlement, said Jue, who added that San Francisco officials expect Precision or its insurance carrier to cover the entire bill.

“We’re committed to protecting the interest of our ratepayers,” he said.

Precision’s work was part of a larger project to overhaul sewers around The City’s west side. The firm also worked on portions of 20th Avenue, 35th Avenue, 47th Avenue, and Rivera and Santiago streets, according to the Department of Public Works.